Aims: Diet may affect the risk of several chronic human diseases but additional research is needed. This project has two main thrusts. One is the study of diet-cancer relations; the other is the study of diet in relation to risk of amyotrophic lateral sclerosis (ALS). Accomplishments: Defects in antioxidant defenses (e.g., superoxide dismutase 1 [SOD1]) are a cause of ALS, thus it is reasonable to suspect that antioxidant intake may also affect the incidence or progression of this disease. Regarding diet and ALS, one thrust has been an analysis of dietary data from Dr. Kamel's case-control study of ALS (published this year). A second study of the same the relation is an add-on to a large cohort study underway at the National Cancer Institute. The cohort consists of members of the American Association of Retired Persons (AARP) who have completed a dietary questionnaire (approximately 600,000 people). We expect about 150 cases of amyotrophic lateral sclerosis to develop in this cohort by 2002.